Content of high bio available carotenoids in tomato-based products

The most abundant carotenoids present in tomato-based products were taken into account. Several samples coming from Italian stores have been analysed by using an RP – HPLC method. These products show a free carotenoids content proportional to the intensity of the manufacturing processes to which there are subjected. Among the carotenoids lycopene isomerises in various cis forms under different chemical – physical conditions. The lycopene antioxidant activity appears to be related to its trans – cis isomerisation degree, and the stability and the relative abundance of the isomers were investigated by applying heating and illumination. The cooking process seems to increase the total lycopene availability, whereas a prolonged exposure to a light source appears to be the best way to obtain the cis isomers. β-carotene is partially subjected to degradative processes, and do not shows an appreciable isomerisation degree under the same conditions.